Compile unison 2.48.4 build with OCaml version 4.08.1 on Manjaro

Question

I need a specific unison version compilied with a specific OCaml version to work together with the unison package on Ubuntu Server 20.04 LTS. I need unison 2.48.4 build with OCaml version 4.08.1. The package in AUR seems to be build with another OCaml version and cannot be used in my case.

In the repositories of Manjaro only unison 2.52 and OCaml version 4.13.1 are available and currently installed on my system.

Can somebody give me newbie-dummy guide how to install and build with specific versions of both programs? And where I get the source files from?

Thank you very much.

Answer 1

You should install OCaml through opam (if you already have an OCaml installation, delete it completely before installing through opam)

Once you have opam installed (don't forget to opam init ), you can install the compiler version (in the default switch) you want with

opam install ocaml-compiler.<version>

You can list all the available compilers with

opam switch list-available

And you can even create a local switch with

opam switch create <version>

So in your case it would be

opam install ocaml-compiler.4.08.1

or

opam switch create 4.08.1

Then if you want to install a specific version of a package just do

opam install <package>.<version>